The Long History of Old Ageedited by Pat Thane320pp, Thames & Hudson, £25

At the heart of this sumptuous book lies a revelation that sets all our suppositions about old age in a new perspective. It has become commonplace to think we live in times uniquely populated by old people. The easy assumption is that in classical times, a few old crones survived, inspiring legends about Teiresias and Methuselah; that in the Middle Ages practically everyone was dead by 50, carried off by plagues and wars; that 19th-century industrialisation killed off miners and factory workers before they could grow old, and that only today are the old a conspicuous and sturdy part of our communities. This book refutes such generalisations chapter by chapter and with copious illustrations, taking us through European history from the Greeks and Romans, via the Middle Ages, Renaissance and the Enlightenment, until the present day.

"Recent research drawn from qualitative investigations" and "modern demographic techniques" are mentioned but not explored. Instead we are given the statistics: in 1AD, over-60s made up 6 to 8% of the Roman empire; in 17th-century Europe they comprised 10%. Life-expectancy figures from earlier centuries, heavily loaded with deaths in infancy, have given us the wrong impression. In fact once you survived into early maturity you could expect to live to a decent age. Right through the centuries, old age had been designated at about 60 or 70. The biblical three score years and 10 set the standard. Only in the 20th and 21st centuries has this changed significantly.

"The old" is the most baggy and shapeless of definitions. It takes in everyone from 50 to 100 (more if you hale from Georgia). Too often the old are lumped together by younger generations who expect that being over 50, let alone more than 70, will somehow take them across a frontier into another type of existence. This book gives ample evidence that this just isn't so.

Writing when he was 62, Cicero enumerated the advantages of age, especially in political life. By cooling the passions of youth it allows the mind to concentrate on serious matters. The passing of sensual pleasure means virtue can come to the fore. Centuries earlier Socrates had taken a more negative view, calling the old pessimistic, distrustful, malicious, suspicious and small-minded ... attributes that might well suit them for politics, too. Plenty thought so: the average age of the Venetian doges between 1400 and 1600 was 72. Sparta, briefly, had a gerontocracy. The law-maker Moses was old, so were Old Testament prophets. Popes have almost always been old. And God has rarely appeared without his white beard. The aged, powerful and male have had it their own way throughout history.

But these essays point up another story. Old women have been regarded and depicted in a far less generous way than men. Greek and Roman dramas mocked them. Medieval allegorical pictures showed the virtues as young and beautiful, the vices as old and ugly. It was said that a menopausal woman could wither fruit on the vine, or crack a mirror. Widows living alone and scratching a wretched living were denounced as witches. There were glorious exceptions, usually prosperous and well connected. Hildegard of Bingen founded her community of nuns when she was 67 and stayed at its head until her death at 81. Sofonisba Anguissola, one of the most accomplished artists of the 17th century, was denied the chance to study life-drawing so used herself as model. The self-portrait of her aged 78 shines out, unsentimental and honest. She lived to be 92.

The old have always been at the margins of society but their place in the greater scheme of things has varied. In religious times they were seen, with a certain gravitas, as at the threshold of death, facing the prospect of the last judgment and eternal life. They were tended in their infirmities by the religious communities which not only offered them prayers and spiritual solace, but set up the first hospitals for their care. The church was the first institution to have something like a pension scheme for its retired workers, the clergy. Everyone else was dependent on the generosity of their children, a classical virtue more often honoured in theory than practice.

With the Enlightenment, such emphasis changed. The emerging secular world began to value life for itself. The French revolution instituted a Fête de la Vieillesse, and drew up the first plans for social welfare. Civil servants got government pensions. The idea of the religious retreat gave way to the concept of retirement. The upper classes fared well, with improving diets, comfort and hygiene. But the ideals were slow to reach the poor, who were all too often dependent on charity. Photographs of their serried ranks in St Pancras and Marylebone workhouses break the heart.

But medicine was changing their lives too. Galen had set the tone with his view that old age was not a disease, but nor was it complete health either. His recommendations included reading aloud, ball-throwing and travel on a ship. Modern cruise liners please note. It had been assumed that old age unavoidably meant infirmity and the idea of seeking to cure its sicknesses was somehow against nature. In the 20th century, the increasing medicalisation of old age meant that many more stayed fit as they lived longer. Today the frontier of change is how we judge the quality of lives, artificially prolonged by medicine, which previous centuries would have let slip quietly away. Dante compared death to a ship lowering its sails as it enters harbour. That image and many rich and beautiful illustrations will stay with me through my own declining years.